Field of the Invention
The present invention generally relates to an apparatus and method for transporting wafers between a wafer carrier and a process tool under vacuum, including an apparatus and method for opening and closing a FOUP (front opening unified pod) under vacuum.
Description of the Related Art
Recently, some platforms for handling semiconductor wafers have begun opening/closing a FOUP in a N2 atmosphere so as to reduce the number of particles adhering to wafers unloaded from and loaded to the FOUP. If the opening/closing of the FOUP is operated under vacuum, the particle issue is expected to be solved remarkably. However, the conventional opening/closing mechanism is designed for use in standard atmosphere, and is not operable under vacuum for the following reasons: The mainstay of semiconductor automation is shuttling products (e.g., silicon wafers or quartz photo-masks) between ultra-clean storage carriers (e.g., a FOUP) and a variety of process tools (e.g., processing, measurement, or testing chambers) through an equipment front end module (EFEM) such as a minienvironment. A FOUP is installed in a load port which is gas-tightly attached to a minienvironment via an interface. After the FOUP is connected to the minienvironment, a door of the FOUP facing the interior of the minienvironment opens to the interior by unlatching the door (releasing a lock of the door) and moving the door away from the FOUP and then moving it downward to fully open the FOUP. This process is illustrated in FIG. 1. FIG. 1 is a schematic representation of a conventional load port with a FOUP when a door of the FOUP is opened (the structure of a minienvironment is not shown). An opening/closing device (now shown) releases a door lock of a FOUP 1 installed in a load port 2 and holds a door 3, and then moves the door 3 downward to secure a space for robotic operation wherein the door is held in a support 4. In the above, the opening/closing device uses a motor for unlatching and moving the door. Since the moving parts including the motor are provided with grease which tends to evaporate under vacuum, the moving parts need to be sealed from the vacuum environment. However, the minienvironment uses standard atmosphere, and thus, it is difficult to completely seal the moving parts including the motor in its entirety while moving the door with complex operating mechanisms. Further, since the door is moved downward to open the FOUP, a significant amount of space is required for the vertical movement of the door. In this disclosure, the “door” may also be referred to as “cover”.
An object of the present invention is to resolve at least one of the above-addressed problems.
Any discussion of problems and solutions in relation to the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.